1. Field of the Invention
The present invention relates to an apparatus for and a method of externally displaying the operating state of a refrigerator, and more particularly to an external display device of a refrigerator which is configured to achieve a serial data transfer with a control unit of the refrigerator. Also, the present invention relates to a method for controlling such an external display device.
2. Description of the Conventional Art
Home electronic appliances such as refrigerators are widely used by a variety of consumers having a variety of tastes. In order to satisfy such a variety of tastes of consumers, manufacturers of such home electronic appliances manufacture appliances having multiple functions.
For example, in the case of refrigerators, many development efforts have been made to add auxiliary functions to the basic functions of a refrigerator, or to provide a function for selectively using the basic functions of the refrigerator, thereby providing a power saving function to the refrigerator.
One such auxiliary function is to display information associated with the current operating state of a refrigerator or other states, thereby enabling a user to recognize those states. The present invention relates to an external display device having such a function.
The externally displayed information may include the current temperature and set temperature of a refrigerating or freezing compartment, an indicator based on the amount of generated cold air, the use or non-use state of the refrigerating or freezing compartment or a fresh compartment, and erroneous states of elements required for a freezing cycle.
Problems involved in conventional external display devices employed in refrigerators will now be described.
FIG. 1 is a block diagram illustrating the configuration of a refrigerator to which a conventional external display device is applied.
As shown in FIG. 1, the refrigerator includes sensors S1 and S2 adapted to sense the temperature of a refrigerating or freezing compartment, a compressor 16 used in the freezing operation of the refrigerator, a fan motor 17 operatively connected to the compressor 16 and adapted to circulate cold air through the refrigerating or freezing compartment, and a defrosting heater 18 adapted to remove frost formed before and after the freezing operation.
The refrigerator also includes a microprocessor 12 for controlling operations of the compressor 16, fan motor 17 and defrosting heater 18 in accordance with temperatures detected by the sensors S1 and S2, buffers 13 and 14 for temporarily storing data output from the microprocessor 12, and ten signal lines L1 to L10 for transmitting data output from the buffers 13 and 14 in a parallel manner to an external display device 20.
The microprocessor 12 and buffers 13 and 14 constitute a control unit 10, along with another buffer 15 which will be described hereinafter.
As shown in FIG. 2, the external display device 20 is mounted on the outer surface of a refrigerator door. The external display device 20 is configured to display a key manipulation of the user and the current state of the refrigerator. This external display device 20 includes a plurality of light emitting elements LED1 to LEDn, and a plurality of diodes D1 to Dm. These light emitting elements LED1 to LEDn and diodes D1 to Dm are connected in a combined manner to the signal lines L1 to L10 adapted to transmit data output from the control unit 10. For example, the light emitting element LED1 is coupled between the first and seventh signal line L1 and L7 whereas the light emitting element LED2 is coupled between the second and seventh signal line L2 and L7.
Accordingly, the light emitting elements LED1 to LEDn turn on selectively, to perform a light emitting operation, in accordance with parallel data from the buffers 13 and 14 applied thereto via the ten signal lines L1. The diodes D1 to Dm turn on selectively by the parallel data applied thereto.
The external display device 20 also includes a plurality of keys K1 to K12. These keys K1 to K12 are connected to signal lines in a manner similar to that in the case of the light emitting elements LED1 to LEDn. For example, the key K1 is coupled between the first and eleventh signal lines L1 and L11 whereas the key K2 is coupled between the first and twelfth signal lines L1 and L12.
The diodes D1 to Dm serve to prevent backward current from being generated.
When one of the keys K1 to K12 is selected by the user, a key signal in the form of voltage is generated. This key signal is sent to the microprocessor 12 which, in turn, detects the selected key based on the key signal.
The signal lines L11 and L12 are also included in the external display device 20 in order to transmit key signals generated from selected keys to the control unit 10. The external display device 20 further includes a buffer 15 for temporarily storing key signals received from the signal lines L11 and L12 and then outputting the key signals to the microprocessor 12.
A supply voltage source 11 is also provided to supply a drive voltage to the microprocessor 12.
FIG. 2 is a perspective view illustrating the outer construction of a general refrigerator in which the external display device 20 is installed.
As shown in FIG. 2, the external display device 20 is mounted on the outer surface of a refrigerator door 25 hingably mounted to a refrigerator body by a hinge. The control unit 10, which serves to control the operation of the refrigerator, is mounted in the inner portion of the refrigerator body. The control unit 10 also serves to control the external display device 20.
The external display device 20 is coupled to the control unit 10 by signal lines L1 to L12. The signal lines L1 to L12 extend through a hinge hole 31 formed at the hinge.
Signal processing operation of the external display device having the above-mentioned configuration will now be described.
The light emitting operation of the light emitting elements LED1 to LEDn based on data output from the microprocessor 12 will be described first.
When the microprocessor 12 receives signals from the sensor S1 and S2 indicative of the temperature of a refrigerating or freezing compartment, it determines the state of the refrigerator, and then controls operations of the compressor 16, fan motor 17 and defrosting heater 18 in accordance with an appropriately set program.
The microprocessor 12 also sends data to be displayed, such as the compartment temperature or current operation state of the refrigerator, to the external display device 20 via a selected one of output terminals OUT1 to OUT10 in the form of a signal of a certain voltage level.
The output signal is temporarily stored in the buffers 13 and 14 and then transmitted to the external display device 20 mounted on the refrigerator door 25 via a selected one of the signal lines L1 to L10. Based on the transmitted signal, a selected one of the light emitting elements LED1 to LEDn emits light.
As the selected light emitting element emits light in accordance with the above-mentioned procedure, the data output from the microprocessor 12 is displayed, so that the user can recognize the current state of the refrigerator. In this case, the display operation of the external display device 20 is carried out irrespective of a key manipulation of the user. In other words, this case corresponds to a case in which the microprocessor 12 operates to display information about the operating state of the refrigerator, etc. in accordance with a program set therein. The information may include the refrigerating or freezing compartment temperature detected by the sensors S1 and S2, and an indicator indicating the amount of generated cold air.
Now, a signal transmission procedure will be described which initiates the point of time when the user manipulates an optional key on the external display device 20 to when the microprocessor 12 of the control unit 10 detects the selected key.
The microprocessor 12 sequentially outputs high-level signals at its output terminals in such a manner that there is no data collision in the signal lines L1 to L12 along which data inputting/outputting is carried out. The outputting of a high-level signal is carried out under the condition in which the microprocessor 12 recognizes the output line to which the signal is transmitted.
When the user selects an optional key on the external display device 20, a current path is established between the selected key and the microprocessor 12 via one of the eleventh and twelfth signal lines L11 and L12. Accordingly, the signal output from the microprocessor 12 flows along the established current path, so that it is fed back as an input key signal to the microprocessor 12 via the signal line L11 or L12. Based on the input key signal, the microprocessor 12 detects the selected key.
Where the input key signal is associated with a certain control, the microprocessor 12 carries out the control. Where the input key signal is associated with a display of certain information, the microprocessor 12 detects the state of the refrigerator associated with the information to be displayed and outputs a signal for driving light emitting elements selected to display the information. The outputting of the signal is carried out in the same manner as mentioned above.
Thus, information according to the key selected by the user is displayed on the display panel of the external display device 20.
Therefore, in accordance with the external display device of the refrigerator, the user can recognize the operating state of the refrigerator without opening the door of the refrigerator. It is also possible to apply a signal for adjusting the operating state of the refrigerator to the control unit of the refrigerator without opening the door of the refrigerator.
However, the above-mentioned conventional external display unit uses a parallel communication system for communications between the external display unit and control unit. Due to the use of such a parallel communication system, an increase in the number of functions to be displayed results in an increase in the number of signal lines to transmit signals associated with those functions. However, such an increase in the number of signal lines is problematic.
As shown in FIG. 2, the signal lines L1 to L12, which are used to transmit signals between the control unit 10 mounted in the refrigerator body and the external display device 20 attached to the outer surface of the refrigerator door, extend through the hinge hole 31 of the hinge 30. In such a configuration, an increase in the number of signal lines results in a difficulty in inserting those signal lines into the hinge hole 31. Furthermore, the limited size of the hinge hole 31 limits the number of signal lines that can be inserted into the hinge hole 31. This results in a limitation in the quantity of data that can be displayed on the external display device 20.
Where the external display device 20 is spaced apart from the control unit 10 by a great distance, signal lines having a great length must be used. This results in an increase in manufacturing costs.